1. Field of the Invention
The present invention relates to a substrate cleaning method and a substrate cleaning device for subjecting a substrate to predetermined processing.
2. Description of the Background Art
In photolithographic processes in manufacturing processes of semiconductor devices, liquid crystal displays and so on, resist films are first formed on substrates. The resist films formed on the substrates are subsequently exposed in predetermined patterns. The substrates that have been subjected to exposure processing are then subjected to development processing, so that resist patterns are formed on the substrates.
A developing device is used for performing the foregoing development processing. The developing device includes a spin chuck that horizontally holds the substrate and rotates the substrate around an axis in a top-to-bottom direction, a developing liquid nozzle that supplies a developing liquid to the substrate and a rinse liquid nozzle that supplies a rinse liquid to the substrate. During the development processing, the developing liquid nozzle moves from outside of the substrate to a position above the center of the substrate while discharging the developing liquid with the substrate rotated by the spin chuck (see JP 2005-210059 A, for example).
In this case, the developing liquid is supplied onto the entire substrate, and a liquid layer of the developing liquid is formed to cover the resist film on the substrate. In the state, dissolution reaction of the resist film on the substrate proceeds. Then, the rinse liquid nozzle moves to the position above the center of the substrate so as to replace the developing liquid nozzle, and discharges the rinse liquid for a predetermined period of time. This causes the developing liquid on the substrate to be removed. When the supply of the rinse liquid onto the substrate is stopped, the substrate is rotated at high speed by the spin chuck, thereby causing the liquid on the substrate to be shaken off (spin drying).
Circuit patterns required for manufacturing a semiconductor device are exposed on the substrate with the liquid layer of the developing liquid formed thereon. Therefore, after the dissolution reaction of the resist film on the substrate proceeds, there exist both portions on which a resist pattern is formed and portions on which a resist pattern is not formed. In this case, a surface of the portion on which the resist pattern is formed has hydrophilicity, and a surface of the portion on which the resist pattern is not formed has hydrophobicity.
Therefore, a drying time differs in the portion having hydrophilicity (hydrophilic portion) and the portion having hydrophobicity (hydrophobic portion) during the spin drying, and the rinse liquid may remain on the hydrophilic portion although the hydrophobic portion is dried.
In this case, droplets of the rinse liquid shaken off from the hydrophilic portion adhere to the dried hydrophobic portion. It is difficult to shake off fine droplets adhering to the hydrophobic portion by a centrifugal force. As a result, when the substrate is unevenly dried with remaining fine droplets after the spin drying, reaction products such as water marks are produced, leading to processing defects of the substrate.